WO1994002238A1 - Magnetic stirring system - Google Patents
Magnetic stirring system Download PDFInfo
- Publication number
- WO1994002238A1 WO1994002238A1 PCT/GB1993/001479 GB9301479W WO9402238A1 WO 1994002238 A1 WO1994002238 A1 WO 1994002238A1 GB 9301479 W GB9301479 W GB 9301479W WO 9402238 A1 WO9402238 A1 WO 9402238A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- stirrer
- container
- stirrer bar
- bottle
- magnets
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F33/00—Other mixers; Mixing plants; Combinations of mixers
- B01F33/45—Magnetic mixers; Mixers with magnetically driven stirrers
- B01F33/452—Magnetic mixers; Mixers with magnetically driven stirrers using independent floating stirring elements
Definitions
- This invention relates generally to a magnetic stirring system and in particular to a magnetic stirrer and a method of magnetically stirring a liquid within a closed container.
- Magnetic stirring of liquids wihin a closed or sealed container is a well known technique.
- a stirrer bar in the liquid to be stirred is moved with a stirring action by a magnetic field producinq means outside the container,
- the magnetic field producing means outside the container may be motor driven magnets or solid state switched coils.
- the stirrer bar used hitherto in such systems is of relatively high quality, being strongly magnetised and costly to manufacture. Accordingly, it is normal to recover the stirrer bar after use and wash it for further use.
- a magnetic stirrer comprising a stirrer bar of relatively low power magnetisation for location in a liquid to be stirred within a container, a permanent magnet means of relatively high power for location outside the container in close proximity to the stirrer bar within the container, and driving means for continuously moving the external permanent magnet means so that its strong magnetic field causes the weakly magnetised stirrer bar to move with a stirring action.
- a method of magnetically stirring a liquid within a container according to which a stirrer bar of relatively low power magnetisation is located within the liquid and, outside the container, a permanent magnet means of relatively high power is continuously driven in a movement which causes its strong moving field to move the weakly magnetised stirrer bar within the liquid with a stirring action.
- the invention is based on the realisation that an infallible magnetic coupling between an internal stirrer bar and an external magnetic driver can be achieved, with a low cost stirrer bar of low magnetisation, provided that the necessary coupling can be ensured by use of a high power magnetic drive.
- a reliable magnetic coupling between the stirrer bar and its magnetic driving means is an essential requirement, because the bottle containing the sample is effectively opaque, so that visible checking of the operation of the stirrer bar is virtually impossible.
- the stirrer bar is of relatively low power, it can be sufficiently cheaply made to be disposable with the liquid container.
- the stirrer bar is moulded wholly of ferrite in non-isotropic form.
- a more powerfully magnetised bar using isotropic ferrite can be produced, but manufacture involves orientating the ferrite during moulding, and this is a costly procedure.
- Such a more powerfully magnetised stirrer bar could therefore not be treated as disposable in the context of the market relating to culture bottles.
- the external magnetic drive must be of such compensatory high power as to ensure a reliable magnetic coupling. This is preferably achieved by use of a pair of spaced high power magnets respectively with north and south poles adjacent the stirrer bar. Rare earth magnets are preferred, in particular of neodymium boron.
- the stirrer bar is preferably magnetised along its longitudinal axis and in use extends longitudinally across the base of the container.
- the external permanent magnets more especially of neodymium boron, then preferably extend generally normally to the base of the container with spaced centres, and the driving means acts to rotate the magnets about an axis parallel to the lengths of the magnets and generally central between said magnets.
- a container 10 for example a bottle containing a culture 12, for example a blood culture, has placed within it an inexpensive stirrer bar 14 consisting of a weak magnet moulded wholly of ferrite in non-isotropic form. Because the stirrer bar 14 is cheaply manufactured, it is disposable with the culture bottle 12 after use.
- the stirrer bar 14 is moved with a stirring action within the blood culture 12 by an external magnetic driver generally referenced 16.
- the magnetic driver 16 In order to compensate for the weak magnetic power of the stirrer bar 14, the magnetic driver 16 must be of very high power, and consists of two permanent magnets 18, 20 of neodymium boron, arranged in spaced parallel relationship one with its north pole and one with its south pole adjacent the stirrer bar. These strong permanent magnets 18, 20 are driven in rotation as an assembly about an axis 22.
- the stirrer bar is a 20 mm long cylindrical component of 6 mm diameter, magnetised along its longitudinal axis, and the permanent magnets 18, 20 are each of 6 mm length and 4 mm diameter, being spaced at about 18 mm centres.
- the coupling action is achieved through the base of the bottle 10.
- the invention is also useful in other fields, not only involving other hazardous liquids to be stirred which may make recovery of the stirrer bar undesirable, but as an alternative, for example, to the complex engineering to be found in shaker/incubators extensively used in microbiological laboratories.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/373,254 US5586823A (en) | 1993-02-17 | 1993-07-14 | Magnetic stirring system |
AU45775/93A AU4577593A (en) | 1992-07-20 | 1993-07-14 | Magnetic stirring system |
DE69310915T DE69310915T2 (en) | 1992-07-20 | 1993-07-14 | MAGNETIC STIRRING SYSTEM |
EP93916072A EP0653960B1 (en) | 1992-07-20 | 1993-07-14 | Magnetic stirring system |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/GB1992/001327 WO1993003178A1 (en) | 1991-08-02 | 1992-07-20 | Microorganism growth |
GBPCT/GB92/01327 | 1992-07-20 | ||
EP93301171.0 | 1993-02-17 | ||
EP93301171 | 1993-02-17 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1994002238A1 true WO1994002238A1 (en) | 1994-02-03 |
Family
ID=26134179
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1993/001479 WO1994002238A1 (en) | 1992-07-20 | 1993-07-14 | Magnetic stirring system |
Country Status (2)
Country | Link |
---|---|
AU (1) | AU4577593A (en) |
WO (1) | WO1994002238A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8389274B2 (en) | 2002-03-16 | 2013-03-05 | Bactest Limited | Method and apparatus for the non-invasive monitoring of gas exchange by biological material |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3138370A (en) * | 1963-03-04 | 1964-06-23 | Thermolyne Corp | Magnetic stirring device |
DE1757099A1 (en) * | 1968-03-30 | 1971-03-18 | Herbert Dr Ganster | Stirring device |
US3645506A (en) * | 1969-07-30 | 1972-02-29 | Micro Metric Instr Co | Sampling supply device having magnetic mixing |
US4090263A (en) * | 1975-02-28 | 1978-05-16 | Beckman Instruments, Inc. | Magnetic mixing apparatus |
DE2914170A1 (en) * | 1979-04-07 | 1980-10-16 | Janke & Kunkel Kg | Laboratory magnetic stirrer - having permanent magnet attached to rotor with axial magnetisation giving better control of both long and short agitator elements |
-
1993
- 1993-07-14 WO PCT/GB1993/001479 patent/WO1994002238A1/en active IP Right Grant
- 1993-07-14 AU AU45775/93A patent/AU4577593A/en not_active Abandoned
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3138370A (en) * | 1963-03-04 | 1964-06-23 | Thermolyne Corp | Magnetic stirring device |
DE1757099A1 (en) * | 1968-03-30 | 1971-03-18 | Herbert Dr Ganster | Stirring device |
US3645506A (en) * | 1969-07-30 | 1972-02-29 | Micro Metric Instr Co | Sampling supply device having magnetic mixing |
US4090263A (en) * | 1975-02-28 | 1978-05-16 | Beckman Instruments, Inc. | Magnetic mixing apparatus |
DE2914170A1 (en) * | 1979-04-07 | 1980-10-16 | Janke & Kunkel Kg | Laboratory magnetic stirrer - having permanent magnet attached to rotor with axial magnetisation giving better control of both long and short agitator elements |
Non-Patent Citations (2)
Title |
---|
DATABASE WPI Week 7233, Derwent Publications Ltd., London, GB; AN 72-53340 * |
DATABASE WPI Week 9123, Derwent Publications Ltd., London, GB; AN 91-165821 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8389274B2 (en) | 2002-03-16 | 2013-03-05 | Bactest Limited | Method and apparatus for the non-invasive monitoring of gas exchange by biological material |
US8795982B2 (en) | 2002-03-16 | 2014-08-05 | Bactest Limited | Method and apparatus for the non-invasive monitoring of gas exchange by biological material |
Also Published As
Publication number | Publication date |
---|---|
AU4577593A (en) | 1994-02-14 |
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